I had a two inch krausen on the starter I made last night from a half pint of trub I had gotten from my last batch. I had no idea this could happen so quickly, is that normal??? 1/2 cup DME boiled in 2 cups water for 15 min. cooled to 70 and pitched.

Yes, lots of yeast means a fast start for fermentation. The lag you normally see is the growth phase.

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